vela@ht basis than soft tissues.
We ighed samples of tissues in pliofilm bags vere dried
overnight eat 1009 C and sent to the Applied Fisheries Laboratory in Seattle for processing,which was usually accomplished
about a month efter collecting.
In processing,
the samples in pliofilm bags were applied
to the plates(1 1/2-inch stainless steel, previously weighed),
ashed overnight at 500° - 550° C, slurried vith alcohol, and
dried.
The plated ash received a few drops of Pormvar
dissolved in ethylene dichloride (up to 1 mg dry equivalent)
to affix the ash to the plate.
The plates vere then veighed,
and counted in methane gas-flow counters.
Except in the case of rats, counts were corrected back to
date of collection using the decay rate of island soi)
(plate 7542) collected May 15, 195% at Belle (Fig. 5, p. 11).
Por rats the decay correction vas based upon the individual
decay rate for each plate.
Self-absorption correction factors were based upon land
soil collected June 7, 1954 at Edna, the decay curve of which
(plate 9170) appears in Pigure 5, page 1].
Within seven months
after Nectar an increase in average energy necessitated a re-
duction in the self-absorption correction factor for the later
counting. The following tabulation illustrates these changes.
Ash weight
in mg/plate
Self-absorption correction factor for sgun te
Before November 1, 1955 After Nevember 1, 19
3
10
39
190
200
1090
1.9
1.1
1.4
2.1)
2.9
4.3
1.0
1.1
1.3
1.6
1.9
2.5
Geometry and backscatter for the counters and ;lates used
required a combined correction factor of 1.58.
Cotrelidence
correction factors vere determined and apriled for the counters
em loyed. For tne decay curves plate counts were used,
corrected only for coinetdence.
Arplying these correction factors gave vilues in disintegrations per minute per gram (d/m/g) of wet tissue as of the
date of collection.
Processing techniques are further discussed
in UWFL-43 and WT-616.
Three significant figures vere retained
throughout the calculations, finally being rounded to two.
After plotting d/m/g against time the ordinate was in some
graphs calibrated siso in
pr’crocurtes yer kilogram (uc/kg), s9ssuming 1 uc to equa] 2.2 x 16 a/m.